1) Field of the Invention
This invention relates to a lawn cutting machine, and, more particularly, it is concerned with an apparatus for incising the lawn-covered ground surface to form grooves in stripes in such surface as, for example, the lawn-covered fairway of a golf course.
2) Description of Prior Arts
Unlike ordinary farming ground, the lawn-covered ground such as the golf course as mentioned above has so far been not suited for soil-renewing work by plowing and hoeing, etc.. On account of this, it has heretofore been a practice to accelerate growth of the lawn by forming incised grooves in stripes of a predetermined depth in the lawn-covered ground so as to facilitate penetration of water, oxygen in the air, manures, or else into the neighboring area of the roots of the lawn.
As the expedients for forming the incised grooves as mentioned above, there have been known a variety of contrivances such as one, in which planar cutting blades are swingably mounted on a self-propelling vehicle in its forward-backward direction, and this self-propelling vehicle is driven forward in the state of the cutting blades being inset into the soil, while they are being swung back and forth (vide: for example, laid-open Japanese patent application No. 1-101802); or one, in which the cutting blades are rotated to form the incised grooves (vide: for example, laid-open Japanese patent application No. 63-44801, laid-open utility model applications No. 60-179107 and No. 62-91910).
However, with the first-mentioned type of apparatus, wherein the incised grooves are formed by advancing the self-propelling vehicle, while swinging the cutting blades in the forward-and-backward direction, a large power is required, because of high resistance to cutting the soil by the cutting blades, when they are driven forward, with the consequence that the cutting machine must be of a large and complicated construction, which inevitably leads to increase in its manufacturing cost and its weight to possibly damage the lawn, or other undersirable phenomena.
On the other hand, with the second-mentioned type of the lawn cutting apparatus, which forms the incised grooves by rotation of the cutting blades, the resistance to the forward movement of the apparatus is lower than that in the first-mentioned apparatus which moves forward with the cutting blade being set in the lawn-covered ground. On the contrary, however, this type of apparatus produces a large contact-resistance between the cutting blade and the inner surface of the cut grooves, and moreover, it is not always possible to cut the roots of the lawn and other subterranean stems in the ground with the consequent disadvantage such that roots, stems, or soil come up, not infrequently, to the ground surface to make it difficult to finish the incision of the grooves which give good external appearance.